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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Geotechnical and Hvdroloaic Concerns <br /> <br />South Side Spillway. The middle portion of the south side spillway is <br />founded on bedrock. The lower portion of the channel appears to transition onto <br />alluvial material. The spillway is not provided with erosion protection, and has <br />eroded to its present depth over the years. The eroded channel is presently <br />threatening to undermine the access road at one location along the south side of the <br />valley. Under current conditions and during severe flooding, it is expected that <br />additional erosion of the channel banks may occur. Permanent reduction of the <br />reservoir level and continued utilization of the south side spillway is not expected to <br />significantly increase the potential for continued erosion. It is anticipated that under <br />normal operating conditions the typical low flow will be passed through the outlet <br />works, as is the current practice. <br /> <br />Seepage. Seepage has been a known feature of this reservoir for over ten <br />years. According to a 1987 dam inspection report, it occurs at the toe, local point <br />sources, and at the outlet. Our recent site inspection did not reveal significant <br />seepage with the reservoir level at elevation 6413.5. Reduction of the embankment <br />and/or reducing the reservoir capacity is expected to alleviate historic seepage. <br />Seepage is not considered a significant problem for the dam now, and will be less <br />so under a reduced storage level. <br /> <br />24 <br />